ALMA Cycle 0 brightness distributions of the two spin-rotation components of the N = 27–26 transition of C₄H, averaged over the central 4 km s^-1 of each line. The synthesized beam is 0.′′77 × 0.′′61 and the rms per 4 km s^-1 channel is 1.3 mJy beam^-1. Maps are centered on the position of the star, indicated by a cross. Note that most of the ring structure is lost because this emission lies well outside the primary beam of ~23′′, and that a compact structure centered on the star is only clearly visible in the N = 27–26 b line.